A projectile weighing 12 kg flew out of the cannon horizontally at a speed of 500 m / s.

| May 14, 2021 | education

A projectile weighing 12 kg flew out of the cannon horizontally at a speed of 500 m / s. How many meters will the cannon move back if its mass is 1500 kg? The coefficient of friction between the gun and the ground is 0.4.

m = 12 kg.

g = 9.8 m / s2.

Vsn “= 500 m / s.

M = 1500 kg.

μ = 0.4.

S -?

(m + M) * V = m * Vсн “+ M * V” – the law of conservation of momentum in vector form.

Since the gun was at rest before firing, V = 0 m / s.

m * Vсн “+ M * V” = 0.

m * Vсн “= – M * V”.

Let’s find the speed of the gun after the shot V “according to the formula: V” = – m * Vсн “/ M.

V “= 12 kg * 500 m / s / 1500 kg = 4 m / s.

Let us find the acceleration of the cannon on rollback a.

M * a = Ftr = μ * N = μ * M * g.

a = μ * g.

a = 0.4 * 9.8 m / s2 = 3.92 m / s2.

S = V “2/2 * a.

S = (4 m / s) 2/2 * 3.92 m / s2 = 2 m.



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